In recent years, signals of consumer reproduction video data tend to be subjected to digitalization, and the digitalized signals are recorded in various types of media. There is a DVD format that is standardized and is prevalent worldwide as a common format. This DVD standard includes a “DVD video recording standard”, as a standard for recording, that enables to record and reproduce video/audio data on/from rewritable media. While a detailed description thereof, which is given in the written standards, is omitted, the outline of the construction thereof will be given with reference to FIG. 16.
FIG. 16 is a diagram illustrating the construction of a conventional digital video recording/reproduction device.
In FIG. 16, numeral 1 denotes a DVD-RAM disk as a rewritable medium, numeral 2 denotes an MPEG stream recorded on the DVD-RAM disk 1, and numeral 3 denotes a first management information file for collectively managing constituent elements of the MPEG stream 2 and MPEG information (including resolution information for the MPEG stream 2, MPEG stream information indicating the size of each GOP or the like, information of a reproduction start position, information specifying a reproduction section and the like).
Numeral 4 denotes a reading means for accurately detecting and reading an information signal (actual file data) from the DVD-RAM 1 via an optical pickup or the like. Numeral 5 denotes an MPEG decoder which receives the MPEG stream 2 outputted from the reading means 4, decompresses data from the MPEG stream 2, and demodulates and reproduces video data and audio data. Numeral 6 denotes a reading control means for controlling the reading means 4 on the basis of the result obtained by a management information analysis means 7, that is, control information indicating a specified range or the like. Numeral 7 denotes the management information analysis means which obtains part or all of the first management information file 3 for video recording, which is recorded on the DVD-RAM disk 1, from the signal outputted from the reading means 4, and analyzes the obtained data. Numeral 8 denotes a video signal output terminal for outputting reproduced video data. Numeral 9 denotes an audio signal output terminal for outputting reproduced audio data.
In the case of a rewritable information medium such as the DVD-RAM disk 1, there are generally provided recording functions as described below.
Numeral 20 denotes a rewriting means for rewriting the DVD-RAM disk 1 by writing or erasing information relating to the first management information file 3 in/from the disk 1. Numeral 22 denotes a video signal input terminal for receiving a video signal. Numeral 23 denotes an audio signal input terminal for receiving an audio signal. Numeral 21 denotes an MPEG encoder which compresses the video signal inputted from the video signal input terminal 22 and the audio signal inputted from the audio signal input terminal 23, to create an MPEG stream based on the video recording standard. Further, numeral 26 denotes a reproduction section specifying means, through which a user specifies a desired reproduction section. Numeral 27 denotes a reproduction start position specifying means, through which a user specifies a desired reproduction start position. Numeral 25 denotes a management information rewriting specifying means for specifying information of an item of the first information management file 3 recorded on the DVD-RAM disk 1, that is to be rerwritten, or an item to be added, on the basis of the information specified by the reproduction section specifying means 26 or the reproduction start position specifying means 27. Numeral 24 denotes a rewriting control means for controlling the rewriting means 20 so that it rewrites data recorded on the DVD-RAM disk 1 when the data are rewritten into the information specified by the management information rewriting specifying means 25, the information is newly recorded in the MPEG stream 2, or the information is erased from the MPEG stream 2.
An operation of the information signal editing device constructed as described above will be described.
An information signal based on the video recording standard is recorded on the DVD-RAM disk 1. The information signal includes stream data which is constituted by digitalized video signal and audio signal, and the first management information file 3 for managing the stream data. The specification of the stream data is prescribed according to the standard thereof, and the stream data is compressed and decoded on the basis of, for example, an MPEG2. The audio signal is an MPEG audio or a compressed audio based on an AC-3 or the like, and this signal is recorded as a system stream by a dedicated constitution method. (Hereinafter, a description will be given taking the MPEG stream 2 as an example.) The first management information file 3 is recorded on the DVD-RAM disk 1 on which the MPEG stream 2 is recorded, as a single file, with an extension “.ifo”, and is located in a folder in which the MPEG stream 2 is located.
As described above, the first management information file 3 includes the information relating to the constitution of the recorded MPEG stream 2 (such as the information of the size of a GOP as a compression unit, information of an entire volume, information of an amount of a piece of recorded data, the resolution information for the video signal). Further, in the video recording standard, a function of reproducing data on the basis of the result of simple editing of the management information is supported, and the result of the simple editing is also recorded in the management information file.
The simple editing function here is to add information of a specified part to the management information by user's specification of the desired reproduction section, reproduction start position or the like, from the information signal constituted by the MPEG stream and the management information, which is recorded on the DVD-RAM disk or the like. Since there is no need to modify the MPEG stream itself, the operation of the simple editing can be completed in a short time. Therefore, since random accessing, which is a characteristic of a plate-shaped recording medium such as the DVD-RAM 1, is performed quickly, the data which is subjected to the simple editing as described above can be reproduced smoothly regardless of the fact that data on the DVD-RAM disk 1 such as the MPEG stream 2 is not modified.
FIG. 16 illustrates the case of reproduction start position information to show a typical example of the simple editing function. The reproduction start position information is information of a scene specified by a user. The reproduction start position information is usually constituted by reproduction position information of the MPEG stream and, in addition, there are cases where the reproduction start position information is related to a physical or logical position on the DVD-RAM disk 1 to make it possible to smoothly specify a reproduction position, or is constituted by time axis information of video/audio stream data or quantity information of constituent elements.
The information signal recorded on the basis of the video recording standard as described above is outputted from the reading means 4 in the form processible by the MPEG decoder 5 or the like. Generally, the reading means 4 has a DVD-RAM reproduction means or a means for controlling an information medium reproduction means of a personal computer or the like which is incorporated with the DVD-RAM reproduction means, and has a controlling function to accurately read data by a dedicated application, microcomputer or the like, and a processing function such as a file system, whereby the information signal is outputted as reproduction data.
In the signal outputted from the reading means 4, information read by the MPEG decoder 5 is decompressed or the like, whereby data are decomposed. Then, video data is decompressed into original non-compressed video data from the MPEG stream 2, and audio data, when it is compressed, is decompressed into an original non-compressed audio. The respective data are outputted to the outside from the video output terminal 8 and the audio output terminal 9, converted into analog data or the like, and outputted to a monitor and a speaker, whereby a user is able to enjoy the content recorded on the DVD-RAM disk 1.
Further, among the digital signal outputted from the reading means 4, part of data of the first management information file 3 recorded on the DVD-RAM disk 1 is inputted to the management information analysis means 7. The management information analysis means 7 obtains desired management information from the information signal constituted by the MPEG stream 2 and the first management information file 3, which is recorded on the basis of the video recording standard, through the reading means 4. Then, the management information analysis means 7 analyzes information relating to reproduction, among the obtained management information. To be specific, the management information analysis means 7 analyzes information for performing continuous reproduction, information relating to a reproduction start position, and/or information specifying a reproduction section, and sends a required result to the reading control means 6, and the reading means 4 is controlled according to the specified reproduction mode. In this case, while not shown in the drawing, the device may be provided with an interface connecting the same with a user, so as to analyze the reproduction information selected by the user.
For example, the information analysis means 7 searches the selected reproduction start position from a plurality of reproduction start positions, through the first management information file 3 recorded on the DVD-RAM disk 1, and sends the information relating to the actual reproduction start position of the MPEG stream 2 that is recorded on the DVD-RAM disk 1, to the reading control means 6 on the basis of the searched information. The reading means 4 reads data according to the control by the reading control means 6, whereby reproduction at a desired position which is selected by a user becomes possible, so that the user can enjoy a desired reproduction video and audio.
Further, the conventional system as described above has a function of recording data on the DVD-RAM disk 1. In FIG. 16, a video signal and an audio signal inputted to the video input terminal 22 and the audio input terminal 23 are outputted from the MPEG encoder 21 as an MPEG stream. In this case, the video signal and the audio signal are subjected to MPEG compression and system-encoding. The format for the MPEG compression and the system-encoding is standardized in a like manner as that of the MPEG stream 2 and the first management information file 3 recorded on the DVD-RAM disk 1. The information signal outputted from the MPEG encoder 21 is, through the rewriting means 20, recorded on the DVD-RAM disk 1. Concurrently, the constituent content of the MPEG stream 2 is added to the first management information file 3 and, thus, the first management information file recorded on the DVD-RAM disk 1 is rewritten, and a second MPEG stream which is selected from the MPEG stream 2 recorded on the DVD-RAM disk 1 is reproduced on the basis of the rewritten management information file. At this time, even when there is additional data recording, the newly created MPEG file is a single file, and this file is added to the previous MPEG stream 2, and information relating to this added MPEG file is newly registered with the first management information file 3, whereby reproduction can be performed smoothly.
Further, when the simple editing supported by the video recording standard is performed by a user, the first management information file 3 recorded on the DVD-RAM disk 1 is rewritten. That is, for example, when the user specifies a specific section through the reproduction section specifying means 26, the first management information file 3 is rewritten by the rewriting control means 24 and the rewriting means 20, through the management information rewriting specifying means 25, on the basis of the specified range. Similarly, the first management information file recorded on the DVD-RAM disk 1 is rewritten by adding or deleting data to/from the first management information file 3, or modifying the same, on the basis of the information relating to the reproduction start position specified through the reproduction start position specifying means 27. Then, the second MPEG stream which is selected from the MPEG stream 2 recorded on the DVD-RAM disk 1 is reproduced on the basis of the rewritten management information file.
In this way, the first management information file 3 on the DVD-RAM disk 1 is rewritten by the simple editing function. When reproduction is performed, data are read on the basis of the newly rewritten management information file on the DVD-RAM disk 1. For example, when the reproduction start position is specified first, a user can specify the reproduction start position as well as specifying for general reproduction, and thus there is no need to search data requiring long reproduction time or the like, for the reproduction start position, resulting in instant data reproduction at the desired reproduction start position.
In this case, it is usual that the management information file 3 is rewritten when the simple editing or the like is finished, and the updated management information file is applied when reproduction is performed. Specifically, in order to protect the rewriting into the updated management information file from occurrence of power failure, an operation of ejecting a commutative disk such as the DVD-RAM disk 1 or the like, the rewriting of the DVD-RAM disk 1 is instantly carried out with the operation of specifying rewriting of the first management information file 3.
As described above, when the simple editing is performed, the rewriting of the management information file recorded on the DVD-RAM disk 1 has been required.
However, the above-described construction has a problem that it is impossible to carry out the simple editing when the information signal cannot be rewritten. To be specific, when the so-called write-protect such as a process of prohibiting writing on the DVD-RAM disk 1 is applied to protect the information signal written on the DVD-RAM disk 1, the first management information file 3 on the DVD-RAM disk 1 cannot be rewritten. Accordingly, it is impossible to carry out the simple editing as described above making full use of the characteristic of the disk, in which a reproduction start position at user's request is specified so that reproduction is performed from the specified position without rewriting the MPEG stream 2.
Further, in the above-described construction, while the information signal can be reproduced, it may be impossible to create an arbitrary duplicate file that is selected by a user from the information signal recorded on the DVD-RAM disk 1.
Furthermore, when a duplicate of the MPEG stream is created, there is no means for managing the duplicate stream. Therefore, a long time is required for an operation of reproducing the created duplicate stream.
The present invention is made to solve the above-described problem and has for its object to provide a device, a method, and a program for easily editing an information signal regardless of a state of a disk or the like, i.e., whether rewriting of the information signal recorded on the disk is possible or not.